The discussion of the background of the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge at the priority date of any of the claims.
Usually, progressive multifocal lenses have a far distance vision region particularly adapted for far distance vision and a near distance vision region particularly adapted for near distance vision. The far distance vision region provides to the wearer a first refractive power and the near distance vision region provides to the wearer a second refractive power. The far and near distance vision regions are usually linked by a progressive region along which the refractive power progresses continuously.
Such progressive multifocal lenses are well adapted to provide a wearer a clear vision at near distance and far distance and the progressive region provides the wearer with a progressive refractive power so as to see at intermediate distances.
Although the progressive region may be used by the wearer to seek an intermediate distances, the visual comfort of the wearer may be reduced when using the progressive region of the progressive multifocal lens. In particular, the progressive region is usually narrow.
The use of intermediate distance vision increases, in particular since wearers spend more and more time reading on screens such as computer screens.
Existing ophthalmic lenses provide extended intermediate distance vision region. Usually such extension is done at the expense of the comfort of the wearer in other situations of vision.
For example, the extension of the intermediate distance vision region may be obtain by spreading significantly the peripheral aberrations related to the progression, thus directing the distribution of defects to ultra-soft design, resulting in reduced widths of the far and near distance vision regions.
The extension of the intermediate distance vision region may also be obtain by extending the length of progression, which has the effect of reducing the power gradients and thus reducing aberrations, but makes the transition between the different distance vision region uncomfortable.
Therefore, there is a need for a progressive multifocal lens that would provide high degree of visual comfort to the wearer when seeking at far, near and intermediate distances.
An aim of the present invention is to propose such a progressive multifocal ophthalmic lens.